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Phosphorus to horse...
Phosphorus to horses and cows
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- Ögren, Gunilla (author)
- Swedish University of Agricultural Sciences,Sveriges lantbruksuniversitet,Institutionen för husdjurens utfodring och vård (HUV),Department of Animal Nutrition and Management
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(creator_code:org_t)
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- ISBN 9789157691163
- 2013
- English.
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Series: Rapport / Sveriges lantbruksuniversitet, Institutionen för husdjurens utfodring och vård, 0347-9838
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Abstract
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- It is important from a nutritional perspective to meet the phosphorus (P) requirements of animals. From an environmental perspective however, it is important not to feed more P than necessary, because excessive P will mainly be excreted with feces, and the soluble P fraction is vulnerable to runoff losses and may contribute to eutrophication. The recommended dietary P levels to dairy cows have successively decreased over the years but recently, an increase in the requirements to growing horses was suggested because fecal endogenous P losses might be higher than previously estimated. The main aim of this thesis was to assess fecal P losses in growing horses, and in brood mares and dairy cows kept on pasture in Sweden. In paper I, P balance and fecal P losses in growing horses in training fed a forage-only diet ad lib with (HP) or without (LP) P supplementation was studied. In addition, the proportion of the extractable (in dilute HCl solution) inorganic P fraction (Pi) of total P (TP) in feces was assessed. Fourteen Standardbred horses (aged 20 months) were used in a cross-over experiment. Feed intake was measured and spot samples of urine and feces were collected. Acid insoluble ash was used as indigestible marker to assess daily fecal output. Estimated P retention was low (<1.7 g/day) and only that for diet HP was significantly higher than 0 g/d. The fecal endogenous P losses were estimated to be less than 10 mg/kg body weight, which do not support the suggested increase in P requirements. The proportion of Pi of TP was > 85% and Pi increased linearly with P intake. In paper II, TP and Pi in feces from lactating and non-lactating dairy cows (n=167) and brood mares (n=74) kept on pasture was investigated and also the use of P supplements. Samples of feces, forages and pastures biomass were collected. The proportion of Pi of TP was greater for lactating horses than lactating cows (63±4 vs 49±5 %). Supplementation of lactating animals with P generally matched their estimated requirements and was therefore justified, while supplementation of non-lactating animals could not be justified. In conclusion, an increase in P requirement to growing horses seems not to be justified, and the high proportion of Pi in feces from horses indicates that P overfeeding of horses might be potentially more harmful to the environment than P overfeeding of dairy cows.
Subject headings
- LANTBRUKSVETENSKAPER -- Husdjursvetenskap -- Husdjursvetenskap (hsv//swe)
- AGRICULTURAL SCIENCES -- Animal and Dairy Sience -- Animal and Dairy Science. (hsv//eng)
Publication and Content Type
- vet (subject category)
- lic (subject category)
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